Main memory in a system can be setup in various physical configurations to optimize power consumption and performance. Memory may be mirrored for redundancy to mitigate DIMM failures. Fully mirrored memory, while being fully redundant, would cut the capacity of the memory in half vs. non-mirrored memory. However, memory may be selectively mirrored so that a portion of the memory is mirrored, such as that containing information critical to program operation, and the remainder of the memory is non-mirrored.